title: Tracking airborne Legionella and Legionella pneumophila at a biological treatment plant.
abstract: Biological treatment plants are frequently used to degrade organic substances in wastewater from wood refinement processes. Aeration ponds in such plants provide an optimal growth environment for many microorganisms, including Legionella species. To investigate whether legionellae could be dispersed as aerosols from the ponds and transported by the wind, the wetted-wall cyclone SASS 2000(PLUS) and the impactors MAS-100 and STA-204 were used to collect air samples directly above, upwind, and downwind of aeration ponds during a 4-month period. Computational fluid dynamics was used a priori to estimate the aerosol paths and to determine suitable air-sampling locations. Several Legionella species, including Legionella pneumophila, were identified in air samples at the biological treatment plant using microbiological and molecular methods. L. pneumophila was identified up to distances of 200 m downwind from the ponds, but, in general, not upwind nor outside the predicted aerosol paths. The highest concentration level of viable legionellae was identified directly above the aeration ponds (3300 CFU/m3). This level decreased as the distance from the aeration ponds increased. Molecular typing indicated that a single clone of L. pneumophila was dispersed from the ponds during the period of the study. Thus, our study demonstrated that aerosols generated at aeration ponds of biological treatment facilities may contain L. pneumophila, which then can be transported by the wind to the surroundings. The methods used in this study may be generically applied to trace biological aerosols that may pose a challenge to environmental occupational health.
authors.affiliation: Norwegian Defence Research Establishment (FFI), P.O. Box 25, N-2027 Kjeller, Norway. janet-martha.blatny@ffi.no
authors.forename: Janet Martha
authors.initials: JM
authors.lastname: Blatny
authors.forename: Bjørn Anders P
authors.initials: BA
authors.lastname: Reif
authors.forename: Gunnar
authors.initials: G
authors.lastname: Skogan
authors.forename: Oyvind
authors.initials: O
authors.lastname: Andreassen
authors.forename: E Arne
authors.initials: EA
authors.lastname: Høiby
authors.forename: Eirik
authors.initials: E
authors.lastname: Ask
authors.forename: Viggo
authors.initials: V
authors.lastname: Waagen
authors.forename: Dag
authors.initials: D
authors.lastname: Aanonsen
authors.forename: Ingeborg S
authors.initials: IS
authors.lastname: Aaberge
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Caugant
mesh_terms: D000391:Air Microbiology; D003198:Computer Simulation; D004784:Environmental Monitoring; D005618:Fresh Water / Q000382:microbiology; D016952:Legionella pneumophila / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D018508:Water Purification; D014887:Weather